The present invention relates to an improvement of the method and equipment for generating electricity by revolving a dynamo by means of the driving wheel of motor cars.
It is well-known in the conventional method and equipment of this kind that a base plate provided with multiple rollers of small diameter in parallel can be driven by one of driving wheels of a motor car and, after all the other wheels are stopped, the said driving wheel is revolved by the motor car engine to turn the small rollers, whose revolution in turn is transmitted directly or indirectly through a flexible shaft to a dynamo shaft, eventually generating electricity.
According to the conventional method and equipment the driving wheel of the motor car on the small rollers loads a part of the motor car body weight and always presses a certain limited surface area of each roller. For this reason, the driving wheel tire is pressed whenever it contacts the small rollers and released whenever it leaves. These actions are repeated throughout electricity generation. As a result, the frictional resistance between the tyre and the small rollers becomes so large that their temperature rises excessively even if operation is continued for only a few minutes or a quarter of an hour, and the process must be halted.
Of course, such over-heating of the tyre and rollers due to frictional resistance may be prevented either by arranging a number of small-diameter rollers in parallel in an arc surrounding the circumference of the tyre to disperse the frictional resistance or by adopting rollers of large diameter. These countermeasures, however, make the equipment heavier and less portable. In particular, the former is awkward as the arrangement of the small rollers must be adjusted in radius according to the tyre diameter, while the latter is not practical as it will be difficult to let the driving wheel ride on the rollers.
Furthermore, even if the overheating problem can be resolved, the said large frictional resistance between the tyre and rollers will make it difficult to achieve high-speed revolution of the driving wheel. When the clutch of a motor car driving on the road is depressed, the driving wheels continue to revolve due to inertia because of the car body weight and speed, permitting gear changes. On the other hand, the driving wheel revolving on rollers has only a small inertia and therefore it will stop so soon that gear changes may not be possible.
Since driving in low gear or second gear thus becomes inevitable, the speed of the driving wheel will have to be raised to the stipulated speed by accelerating the engine, resulting in an increase in noise and fuel consumption.